Too bad GearSplit is no longer in favor. I loaded it on an old XP machine recently and reacquainted myself with its features. For the first time, I have engine dyno and wind tunnel data (Cd) to accurately arrive at correct gearing for power available. You can guess at Cd or back calculate past runs for a Cd but having the actual number makes for more reliable results. Regardless, what GearSplit did is graph time/distance in feet it took to reach max mph in each gear. Having this feature allowed me to see which gears worked best over a given distance. If I have just three miles of track, I can select gears that give me the most mph for that distance. If I have five miles, the graph tells me if I need to make gear changes. Another great feature is the gear graph itself. Torque values from the dyno are represented by a line and show you if there is sufficient torque to pull gears selected over a given distance. Once the gear line crosses torque line, game over. There is no more mph to be had.

So, if you look at the gear chart along with the time/distance chart, you have a good chance of arriving at correct gears for whatever distance you choose to run. I guess the only problems are; having an old XP machine to run the software and getting Dave Dahlgren to sell you a copy.

Performance Trends sells their Transmission Gear Calculator, which does pretty much the same thing. Plenty of analysis and graphing capability in the Plus version which is what I use. Runs on current Windows software, so no need for a "frankenputer".

Fordboy (Mark?), the Performance Trends software does look similar to GearSplit and by now, would have expected someone to come up with something. Although it may be buried in another part of the software, I did not see a field for entering Cd. Does Performance Trends calculate Cd and does it graph time/distance to reach mph? I only saw a mph/rpm graph. Cd as part of the calculation and a time/distance graph are very important features for we LSR types.

My XP computer is old but still works fine for GearSplit. This may be a good thing because computers running XP are nearly giveaway. No need for an expensive computer to run GS.

Rex, I bit the bullet and took the lakester to Darko in Ogden, UT. It was only 30 miles from I-80 heading home to Wichita so I didn't want to miss the opportunity. Besides, the tunnel came with Tom Burkland who was a very big asset! Cd was .27 but easily improved to .25 with a few additions mocked up in cardboard. There may be more gain yet but time and money prevent this short term. Found a couple of handling improvements too. One was a big handling improvement that gets done first, over all else.

It may not exist but would be helpful if there was an averaged % factor for Cd of rolling wheels that could be applied to wind tunnel data. Not too many rolling ground plane wind tunnels close by and likely well beyond my anemic budget anyway. Woody is the guy who could help out here.

.It may not exist but would be helpful if there was an averaged % factor for Cd of rolling wheels that could be applied to wind tunnel data....

Thanks for the input on your car .

I've looked over the years for the CD you mentioned without much luck. You can find a number of different numbers but I'll bet that ....

F1 and some of the other open-wheel cars know. Look at all that is going on ahead of the open wheel above. None legal of course for a lakester but there might be similar things that can be done inside the inner plane of the wheel/tire. Of course a lot of their aero has more to do with downforce vs. the aero we are looking for.

One might want to look at some of the spreadsheets that I have here ....

... that don't have the time/distance aspect but where you can input different CD's for the body and the wheels. Also you can plot gear changes and see the rpm at any speed amd see if your torque/HP curve is good enough to pull the car at that speed,

.25 Cd is the complete car, with all its warts, in a full scale wind tunnel. Most of the improvement came from a three foot addition to the rear. My car is larger than most G/GL and G/FL competitors because I am old and fat. My engine package allows for a much lower profile car, like yours and Bockscar but I simply don't fit in those cars.

Frontal area is 9 sq. ft. but this includes wheels, suspension and everything else hanging out in the air. One thing about frontal area; it is good to have the lowest FA possible but if by reducing this value, you greatly disturb aero, there could be a net increase in Cd.

... that don't have the time/distance aspect but where you can input different CD's for the body and the wheels. Also you can plot gear changes and see the rpm at any speed amd see if your torque/HP curve is good enough to pull the car at that speed,

Sumner

Hi Sum:

I have used your calculator (thanks Hooley) and Stainless' too. Both were very good and worked well. Both came close to old GearSplit numbers before I knew what my Cd was for certain. Prior to this, I think we used .4 as the Cd when calculating for gears. Pretty standard for an open wheel race car. The time/distance feature was singularly most important. I was able to put together several possible gear combinations that worked. All but one placed maximum mph well past the five mile so those were no good. Only one set put us half way through mile five at max mph and that is the gear package going in the car.

Fordboy (Mark?), the Performance Trends software does look similar to GearSplit and by now, would have expected someone to come up with something. Although it may be buried in another part of the software, I did not see a field for entering Cd. Does Performance Trends calculate Cd and does it graph time/distance to reach mph? I only saw a mph/rpm graph. Cd as part of the calculation and a time/distance graph are very important features for we LSR types.

My XP computer is old but still works fine for GearSplit. This may be a good thing because computers running XP are nearly giveaway. No need for an expensive computer to run GS.

John

Hi John,

Well, I am unfamiliar with the "GearSplit" software. My disclaimer is that I own and use a lot of Performance Trends Software, and have a good relationship with the folks at the company.

There are 12 apps included and one has 52 specialized racing calculators for incredible value. There are 158 of 200 presold and only 4 days left to reach the 200 minimum.Most of these apps are $59 to $79 each so . . . . . . . .

Of course, if you are happy with GearSplit, there is no reason to change if it does what you need. And you don't have to learn any new systems/software/etc, PLUS, there is no cost.

I use data all the time to make decisions. There are other folks who do not. Ya pays yo money, and makes your choice . . . . . . .

Mark

Logged

I used to be a people person. But people changed that relationship.

"There is nothing permanent except change." Heraclitus

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." Albert Einstein

Mark, who told you I am a sucker for a deal? Loose lips, sink ships and in my case, have been torpedoing the old bank account with this car. So, 99 bucks for Bonneville Pro, you say? The cycle never ends.

Mark, who told you I am a sucker for a deal? Loose lips, sink ships and in my case, have been torpedoing the old bank account with this car. So, 99 bucks for Bonneville Pro, you say? The cycle never ends.

John

It is $99 for Bonneville Pro but a whole lot of other stuff as well. Look at the line up, impressive savings if you can use. Includes PipeMax!